GitHub was originally designed for software developers. It lets programmers upload code and share it with other developers. It keeps track of who made what changes where. And it helps merge all those changes together. It “controls” the various versions of an open source software project.
We're going to see this more and more. We're living in a programmed world, so it makes sense to find tools and methods that are working for the programmers around us and try to apply them to solve other problems. It's the hacker way.